For years, Sandor Katz has been fermenting foods, convinced that the probiotics they contain are keeping him healthy despite his compromised immune system.

To hear Sandor Katz tell it, our world would be a very different place without fermented food. It’s not merely that we wouldn’t have much of the fare we cherish most: wine, beer, cheese, yogurt, to name but a few.

Indeed, says Katz, without fermentation and the preservative qualities it imparts, we’d never have built cities, or cars, or iPads, because we’d never have evolved from our hunter-gatherer status. “We could not have developed agricultural societies without the fermenting techniques that allowed us to store food,” says Katz, a tall man of 47, with an unruly mop of hair and thick muttonchops that connect to an equally vigorous mustache.

Fermentation is a process whereby carbohydrates in a food or beverage break down to form alcohol—in the case of wine and beer—or lactic acid, which preserves foods. (In the latter scenario, also called lacto-fermentation, “good” bacteria, or probiotics, drive the transformation.)